Phenolic carbons

Table 15. Strength Properties of Phenolic—Carbon-Fiber Composites...

Caprylic acid, see Octanoic acid Caprylic alcohol, see 1-Octanol Carbitol, see Diethylene glycol monoethyl ether Carbolic acid, see Phenol Carbon disulphide Carbon monoxide Carbon oxysulphide, see Carbonyl sulphide... 

Degrees of polymerization can be calculated from quantitative 13C NMR data by considering the number of substituted (reacted) relative to unsubstituted (not yet reacted) ortho and para phenolic carbons where [5] is the sum of substituted ortho and para carbons and [5] + [f/ is the total ortho and para carbons. The fraction of reacted ortho and para sites is denoted by fs [Eq. (7.2)]. Thus, the number-average number of phenol units per chain Or) can be calculated using Eq. (7.3). This leads to a simple calculation of Mn = x x 106 — 14 ... 

Alkoxide or aryloxide anions are also reputed to be inactive in Sr I reactions. There is, however, one example of such a reaction at an sp carbon the nitro-derivative of 4-nitrocumyl reacts with phenoxide and 1-methyl-2-naphthoxide ions yielding the corresponding ethers (Kornblum et al., 1967). A similar reaction has been reported for halobenzenes in t-butyl alcohol upon stimulation by sodium amalgam (Rajan and Sridaran, 1977). This reaction could not, however, be reproduced (Rossi and Pierini, 1980) and other attempts to make phenoxide ions react at sp carbons have been equally unsuccessful (Ciminale et al, 1978 Rossi and Bunnett, 1973 Semmelhack and Bargar, 1980). It has been found, more recently, that phenoxide ions react with a series of aryl halides under electrochemical induction, but that the coupling occurs at the p- or o-phenolic carbon rather than at the phenolic oxygen (Alam et al, 1988 Amatore et al, 1988). This is... 

Hydrolyzes in soil and water to carbofuran phenol, carbon dioxide, and methylamine (Rajagopal et al, 1986 Seiber et al, 1978 Somasundaram et al., 1989, 1991). Hydrolysis of carbofuran occurs in both flooded and nonflooded soils, but the rate is slightly higher under flooded conditions (Venkateswarlu et al., 1977), especially when the soil is pretreated with the hydrolysis product, carbofuran phenol (Rajagopal et al., 1986). In addition, the hydrolysis of carbofuran was found to be pH dependent in both deionized water and rice paddy water. At pH values of 7.0, 8.7, and 10.0, the hydrolysis half-lives in deionized water were 864, 19.4, and 1.2 h, respectively. In paddy water, the hydrolysis half-lives at pH values of 7.0, 8.7, and 10.0 were 40, 13.9, and 1.3, respectively (Seiber et al, 1978). 

One of the striking features of enzymatic methylation is its exquisite regjoselec-tivity. For example, in the biosynthesis of novobiocin, a methyltransferase NovO catalyzes the methylation of only one of the three phenolic carbons and none of the three hydroxyl groups are methylated (Scheme 7.20). The exquisite regioselec-tivity is also compatible with substrate promiscuity. For example, the methyltransferase CouO from coumermycin A1 synthase catalyzes the methylation of both the mono- and bis-amides [75, 76]. 

Other reported syntheses include the Reimer-Tiemann reaction, in which carbon tetrachloride is condensed with phenol in the presence of potassium hydroxide. A mixture of the ortho- and para-isomers is obtained the para-isomer predominates. -Hydroxybenzoic acid can be synthesized from phenol, carbon monoxide, and an alkali carbonate (52). It can also be obtained by heating alkali salts of -cresol at high temperatures (260—270°C) over metallic oxides, eg, lead dioxide, manganese dioxide, iron oxide, or copper oxide, or with mixed alkali and a copper catalyst (53). Heating potassium salicylate at 240°C for 1—1.5 h results in a 70—80% yield of -hydroxybenzoic acid (54). When the dipotassium salt of salicylic acid is heated in an atmosphere of carbon dioxide, an almost complete conversion to -hydroxybenzoic acid results. They>-aminobenzoic acid can be converted to the diazo acid with nitrous acid followed by hydrolysis. Finally, the sulfo- and halogenobenzoic acids can be fused with alkali. 

The precipitates of PVPh/PDMA from methanol and acetone solutions were examined by CPMAS NMR [51], and evidence for specific interaction was obtained with a 3 ppm shift in the phenolic carbon resonance peak. The proton spin-lattice relaxation times Tj were shorter than those predicted by a linear model, though the rotating frame spin-lattice relaxation times Tjp of the com-... 

Problem 19,14 Assign numbers from 1 for least to 4 for most to indicate the relative acid strengths in the following groups (a) phenol, m-chlorophenol, m-nitrophenol, m-cresol (b) phenol, benzoic acid, p-nitro-phenol, carbonic acid (c) phenol, p-chlorophenol, p-nitrophenol, p-cresol (d) phenol, o-nitrophenol, m-nitrophenol, p-nitrophenol (e) phenol, p-chlorophenol, 2,4,6-trichlorophenol, 2,4-dichlorophenol (/) phenol, benzyl alcohol, benzenesulfonic acid, benzoic acid. ... 

Glycosylation of a flavonoid hydroxy group shifts the phenolic carbon resonance 1-2 ppm upheld and the ort/to-related carbon resonance up to almost 10 ppm (e.g. quercetin) downheld. 

Reaction XXXVI. Condensation of Carbon Tetrachloride with Phenols and simultaneous Hydrolysis (Tiemann-Reimer). (B., 10, 2185.)—This reaction is closely analogous to that of the formation of hydroxy-aldehydes by means of chloroform and caustic alkali (see p. 104). A mixture of a phenol, carbon tetrachloride and caustic soda or caustic potash solution is boiled. Condensation occurs, chiefly in the para-position, but small amounts of the ortho-acids are also formed. The product, after the excess of carbon tetrachloride has been removed, is saturated with carbon dioxide and the unchanged phenol extracted with ether. The hydroxy acids are then precipitated by acidification with hydrochloric acid. 

The flask contained 700.0 mg hydroxocobalamin in 20 ml of water, one funnel 200.0 mg sodium borohydride in 10 ml of water, and another the crude isopropylidine adenosine tosyl ester made from 500 mg isopropylidine adenosine dissolved in 10 ml of 50% aqueous methanol. On adding the borohydride to the vitamin, the color changed instantly from red to brown, then slowly to a greenish black. After 15 min the isopropylidine adenosine tosyl ester was added, and the colour slowly changed to a red-brown. After 45 min at room temperature air was admitted and the mixture was shaken to reoxidise any remaining reduced vitamin B12. The alkaline solution was neutralized with dilute hydrochloric acid and extracted with phenol carbon tetrachloride 3 1 in small portions till the aqueous layer was nearly colorless. The combined extracts were washed with water, mixed with about ten parts of carbon tetrachloride-acetone 10 1 and shaken with small portions of water till all red color was removed. 

This paper present new clathrate equilibrium dissociation pressure data for the binary phenol-carbon dioxide, p-cresol-methane and ternary water-phenol-carbon dioxide over a range of temperatures above the normal melting temperature of phenol and p-cresol. 

The hydrate and phenol clathrate equilibrium data of the water-carbon dioxide, phenol-carbon dioxide, and water-phenol-carbon dioxide systems are presented in Table 1 and depicted in Figure 2. In order to establish the validity of the experimental apparatus and procedure the hydrate dissociation pressures of carbon dioxide measured in this work were compared with the data available in the literature (Deaton and Frost [7], Adisasmito et al. [8]) and found that both were in good agreement. For the phenol-carbon dioxide clathrate equilibrium results, as seen in Figure 2, the dramatic increase of the dissociation pressures in the vicinity of 319.0 K was observed. It was also found in the previous study (Kang et al. [9]) that the experimental phenol-rich liquid-phenol clathrate-vapor (Lp-C-V) equilibrium line of the binary phenol-carbon dioxide system could be well extended to the phenol clathrate-solid phenol-vapor (C-Sp-V) equilibrium line (Nikitin and Kovalskaya [10]). It is thus interesting to note that a quadruple point at which four individual phases of phenol-rich liquid, phenol clathrate, solid... 

For the ternary water-phenol-carbon dioxide system, several interesting phenomena were observed. As shown in Figure 2, the four-phase, water-rich liquid-phenol-rich liquid-phenol clathrate-vapor (Lw-Lp-C-V), dissociation pressures were measured at several temperatures near 293.0 K. Like above the phenol-carbon dioxide clathrate equilibrium results, the dramatic increase of the four-phase dissociation pressures was observed in a vicinity of 293.0 K. One of the most interesting results observed in this work is that a quintuple point at which the five phases of water-rich liquid, phenol-rich liquid, carbon dioxide-rich liquid, phenol clathrate, and vapor coexist in equilibrium was carefully measured and found to be 293.7 K and 57.2 bar. 

Figure 3 shows the clathrate equilibrium measurements for p-eresol-methane and the results are presented in Table 2. Contrary to phenol-carbon dioxide, the clathrate equilibrium dissociation pressure line for p-cresol-methane monotonously increases with temperature. This dependence is similar to that observed with gas hydrates and clathrates. 

A new experimental apparatus was built to measure the clathrate dissociation pressures and equilibrium compositions of liquid phases which coexist with the clathrate phase. The pressure-temperature behavior of the binary phenol-carbon... 

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